FRE-600: Fix code review blockers

- Consolidated duplicate UndoManagers to single instance
- Fixed connection promise to only resolve on 'connected' status
- Fixed WebSocketProvider import (WebsocketProvider)
- Added proper doc.destroy() cleanup
- Renamed isPresenceInitialized property to avoid conflict

Co-Authored-By: Paperclip <noreply@paperclip.ing>

node_modules/level-iterator-stream/UPGRADING.md

@@ -0,0 +1,22 @@
+# Upgrade Guide
+
+This document describes breaking changes and how to upgrade. For a complete list of changes including minor and patch releases, please refer to the [changelog](CHANGELOG.md).
+
+## v4
+
+Upgraded to [`readable-stream@3`](https://github.com/nodejs/readable-stream#version-3xx) which contains several substantial changes and improvements. Since `level-iterator-stream` derives from `readable-stream` we decided to bump major as well.
+
+## v3
+
+Removed support for node 4.
+
+## v2
+
+Encodings were factored out from `levelup` into `encoding-down` and in that process they were removed from this module as well. For more information, please check the corresponding `CHANGELOG.md` for:
+
+- [`levelup`](https://github.com/Level/levelup/blob/master/CHANGELOG.md)
+- [`encoding-down`](https://github.com/Level/encoding-down/blob/master/CHANGELOG.md)
+
+If your code relies on `options.decoder` for decoding keys and values you need to handle this yourself, e.g. by a transform stream or similar.
+
+Support for node 0.10, 0.12 and iojs was also dropped.